Relationship Between Laterality of Orthodontic Miniscrew Failure and Clinical Variables

Background/Objectives: Many reports on orthodontic miniscrew insertion focus on insertion conditions, such as technique, but not on the insertion environment, such as the operator's dominant hand. This study aimed to ascertain whether the operator's dominant hand affects laterality in the success rate of manual and motorized miniscrew insertion methods. Methods: This study retrospectively investigated the medical records of 250 Japanese patients, aged ≥15 years, who underwent miniscrew implantation in the maxilla by right-handed operators with at least 3 years of experience. A cross-tabulation analysis, Chi-square test, and multiple logistic regression analysis were performed to compare the success rates of the two insertion methods. Results: A total of 454 screws were implanted (346 manual and 108 motorized), with an overall success rate of 79.2%. No significant difference was observed in the success rate between the manual (77.7%) and motorized groups (84.2%). Regarding the laterality of the overall success rate, the right-side success rate (84.1%) was significantly higher than that of the left side (75.6%). The right-side success rate in the manual group (82.7%) was significantly higher than that of the left-side (73.0%). In the motorized group, no significant difference was observed between the success rate of insertion on the right (84.6%) and left sides (83.9%). Multiple regression analysis showed that the miniscrew insertion stability was influenced by the insertion side and the operator's years of experience. Conclusions: The manual screw insertion method was susceptible to environmental factors and less successful in left-side insertion by right-handed operators.